The present invention relates in general to slide valves, and in particular to a new and useful flat slide valve having notched guide strips.
The present invention is a flat slide valve, in particular to shut off flow in conveyor lines carrying thickish, powdery or granular media, with a slide plate guide slot provided in the valve housing, the guide slot having laterally limiting guide strip pairs which project into the valve flow channel of circular section and contain at least two mutually spaced notch pairs. Each notch pair has stripping edges interacting with shearing edges at the lower valve plate closing edge when the valve plate is being closed.
A flat slide valve of this design is described e.g. U.S. Pat. No. 4,546,788 (a Swiss patent application No. G 6908/81). The notches of each notch pair are in mutual alignment in the flow direction. During the time the valve is open, medium flushes the mutually aligned notches and the slot portion located between them, whereas the slot area located between the notch pairs forms a practically flowless dam-up space in which solids can deposit. Such deposits of the conveyed medium, depositing particularly on the guide surfaces of the guide strips interrupted by the notches, can be pushed down mechanically by the shearing edges of the valve plate when closing the valve and stripped off in interaction with the stripping edges of the notches in the guide strips, where they are picked up by the medium flow and flushed downstream. But if the valve stays open for a longer period of time, these deposits can solidify and build up into layers so thick in the guide slot portions located between the notch pairs that the application of considerable force is required, when subsequently closing the valve, to effect the scraping off of these deposits. This can prevent proper closing of the valve plate which is guided with as little clearance as possible. Furthermore, scraping off the encrusted deposits can also lead in time to damaging the guide surfaces of the guide strips.